Enhanced Seed Oil Production in Canola by Conditional Expression of Brassica napus LEAFY COTYLEDON1 and LEC1-LIKE in Developing Seeds    

Abstract

The seed oil content in oilseed crops is a major selection trait to breeders. In Arabidopsis (Arabidopsis thaliana), LEAFY COTYLEDON1 (LEC1) and LEC1-LIKE (L1L) are key regulators of fatty acid biosynthesis. Overexpression of AtLEC1 and its orthologs in canola (Brassica napus), BnLEC1 and BnL1L, causes an increased fatty acid level in transgenic Arabidopsis plants, which, however, also show severe developmental abnormalities. Here, we use truncated napin A promoters, which retain the seed-specific expression pattern but with a reduced expression level, to drive the expression of BnLEC1 and BnL1L in transgenic canola. Conditional expression of BnLEC1 and BnL1L increases the seed oil content by 2% to 20% and has no detrimental effects on major agronomic traits. In the transgenic canola, expression of a subset of genes involved in fatty acid biosynthesis and glycolysis is up-regulated in developing seeds. Moreover, the BnLEC1 transgene enhances the expression of several genes involved in Suc synthesis and transport in developing seeds and the silique wall. Consistently, the accumulation of Suc and Fru is increased in developing seeds of the transgenic rapeseed, suggesting the increased carbon flux to fatty acid biosynthesis. These results demonstrate that BnLEC1 and BnL1L are reliable targets for genetic improvement of rapeseed in seed oil production.

Alterations in Seed Development Gene Expression Affect Size and Oil Content of Arabidopsis Seeds

“…flower initiation, which would explain the reduced number of siliques per plant. In this regard, it is interesting to note that overexpression of LEAFY COTYLEDON1 (LEC1) and LEC1-LIKE in Arabidopsis and rapeseed (Brassica napus) under control of the strong seed-specific napin promoter also led to an increase in seed size, but this was accompanied with an abnormal development of the seedlings (Tan et al, 2011). Using truncated versions of the napin promoter, it was possible to separate these two effects, i.e.…”

The OsMYB30 Transcription Factor Suppresses Cold Tolerance by Interacting with a JAZ Protein and Suppressing β-Amylase Expression

“…The measurement of sugar content was performed as described previously with minor modifications (Tan et al, 2011). The soluble sugar in four-leaf stage seedlings was measured at the designated times under the cold stress condition (4°C chamber).…”

Oil and Protein Accumulation in Developing Seeds Is Influenced by the Expression of a Cytosolic Pyrophosphatase in Arabidopsis

“…For example, most transgenic approaches to increase the oil content of seed are composed either of attempts to increase "pull" toward oil biosynthesis through the increased expression of genes controlling plastidic fatty acid biosynthesis or cytosolic glycerolipid assembly (Roesler et al, 1997;Zou et al, 1997;Jako et al, 2001;Vigeolas et al, 2007;Zheng et al, 2008) or by increasing metabolic "push" in this direction through the overexpression of developmental or global metabolic regulators that enhance the expression of genes encoding enzymes of glycolysis and fatty acid biosynthesis (Shen et al, 2010;Pouvreau et al, 2011;Tan et al, 2011). Notable exceptions include the seed-specific expression of class 2 hemoglobins to address oxygen-limiting conditions during the seed maturation phase (Vigeolas et al, 2011).…”